Void closure process due to viscous flow was studied during film formation from high-T latex particles. Steady-state fluorescence and photon transmission techniques were used to probe the evolution of optical clarity during film formation. The latex films were prepared from pyrene (P)-labeled poly( methyl methacrylate) particles and annealed in 10-min time intervals above glass transition temperature. Fluorescence intensity from P was measured after each annealing step. A relation for void closure time versus fluorescence intensity was derived, using the Vogel-Fulcher equation. Viscosity constant B was measured from the above relation and found to be as 11 X 10(3) K. (C) 1997 John Wiley & Sons, Inc.